Method for the Enhancement of Complex Peaks

1. A method of enhanced peak detection in a complex correlation signal, said method comprising the steps of: (a) identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and (b) for each said identified position performing the steps of: (ba) forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; (bb) up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; (bc) searching said up-sampled complex sub-signal for a peak value; and (bd) storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

2. A method according to claim 1 , wherein said parameters comprise at least one of: modulus value of peak value; phase of peak value; and position of peak value.

3. A method according to claim 1 , wherein Fourier interpolation comprises the steps of: fourier transforming said complex sub-signal; zero padding said complex sub-signal; and inverse Fourier transforming said zero padded complex sub-signal.

4. A method according to claim 1 , wherein said complex correlation signal is formed by correlating at least one wideband signal.

5. A method according to claim 1 , wherein said higher resolution is at least two times the resolution of said complex correlation signal.

6. A method according to claim 1 , further comprising: ordering the identified at least one position according to said up-sampled complex signals; and selecting at least one position from the identified at least one position based on said order.

7. An apparatus for enhanced peak detection in a complex correlation signal, said apparatus comprising: means for identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and means for performing, on each identified position, the steps of: forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; searching said up-sampled complex sub-signal for a peak value; and storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

8. An apparatus according to claim 7 , wherein said parameters comprise at least one of: modulus value of peak value; phase of peak value; and position of peak value.

9. An apparatus according to claim 7 , wherein Fourier interpolation comprises the steps of: fourier transforming said complex sub-signal; zero padding said complex sub-signal; and inverse Fourier transforming said zero padded complex sub-signal.

10. An apparatus according to claim 7 , wherein said complex correlation signal is formed by correlating at least one wideband signal.

11. An apparatus according to claim 7 , wherein said higher resolution is at least two times the resolution of said complex correlation signal.

12. A computer-readable medium on which is stored a computer program for enhanced peak detection in a complex correlation signal, said program comprising: code for identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and code for, for each identified position, performing the steps of: forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; searching said up-sampled complex sub-signal for a peak value; and storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

13. A computer-readable medium according to claim 12 , wherein said parameters comprise at least one of: modulus value of peak value; phase of peak value; and position of peak value.

14. A computer-readable medium according to claim 12 , wherein Fourier interpolation comprises the steps of: fourier transforming said complex sub-signal; zero padding said complex sub-signal; and inverse Fourier transforming said zero padded complex sub-signal.

15. A computer-readable medium according to claim 12 wherein said correlation signal is formed by correlating at least one wideband signal.

16. A method of detecting a watermark from a signal, said watermark having a basis pattern embedded, said method comprising the steps of: (a) maintaining a test pattern; (b) correlating said test pattern with said signal to form a complex correlation signal; (c) identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and (d) for each said identified position performing the steps of: (da) forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; (db) up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; (dc) searching said up-sampled complex sub-signal for a peak value; and (dd) storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

17. A method according to claim 16 , wherein said signal comprises one of: audio; image; and video.

18. A method according to claim 16 , wherein Fourier interpolation comprises the steps of: fourier transforming said complex sub-signal; zero padding said complex sub-signal; and inverse Fourier transforming said zero padded complex sub-signal.

19. A method according to claim 16 , wherein said test pattern and said basis pattern are wideband signals.

20. A method according to claim 16 , wherein said higher resolution is at least two times the resolution of said complex correlation signal.

21. An apparatus for detecting a watermark from a signal, said watermark having a basis pattern embedded, said apparatus comprising: means for maintaining a test pattern; means for correlating said test pattern with said signal to form a complex correlation signal; means for identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and means for performing, for each said identified position, the steps of: forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; searching said up-sampled complex sub-signal for a peak value; and storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

22. An apparatus according to claim 21 , wherein said signal comprises one of: audio; image; and video.

23. A computer-readable storage medium on which is stored a computer program for detecting a watermark from a signal, said watermark having a basis pattern embedded, said program comprising: code for maintaining a test pattern; code for correlating said test pattern with said signal to form a complex correlation signal; code for identifying in said complex correlation signal at least one position with a modulus value above a first predetermined value; and code for performing, for each said identified position, the steps of: forming a complex sub-signal by isolating a region of samples of said complex correlation signal, said region comprising substantially equal numbers of samples on opposite sides of said position; up-sampling said complex sub-signal to a higher resolution using Fourier interpolation; searching said up-sampled complex sub-signal for a peak value; and storing parameters associated with said peak value when said peak value is greater than a second predetermined value.

24. A computer-readable medium according to claim 23 , wherein said signal comprises one of: audio; image; and video.